In recent years, studies are being carried out on a mobile communication system in which a radio communication mobile station apparatus (hereinafter simply referred to as “mobile station”) has a relay function (repeater function) that relays a signal directed to another mobile station (e.g., see Patent Literature 1).
In this mobile communication system, for example, the mobile station having the relay function relays a signal directed to the other mobile station transmitted from a radio communication base station apparatus (hereinafter simply referred to as “base station”). This allows even a mobile station that has difficulty in directly communicating with the base station to communicate with the base station via the mobile station having the relay function, and thereby increases system capacity.